1. Field of the Invention
The present invention relates to a switch valve; and in particular, the invention relates to a switch valve to be used for switching between start and stop in feeding a gas.
2. Description of Background Art
The switch valves have been conventionally used in switching between the feeding start and the feeding stop of gases.
In FIGS. 7(a) and (b), a reference numeral 200 shows a switch valve, and the switch valve 200 has a partition wall 211 and a valve body 221.
The partition wall 211 is provided with a hole 212 with which the valve body 221 is fitted.
The valve body 221 is attached to a moving unit (not shown); and when the valve body 221 is seated on the hole 212 by the moving unit, a surface of the valve body 221 closely contacts an inner wall surface (valve seat face 215) of the hole 212, and one space and the other space are separated across the partition wall 211, thereby attaining a closed state (FIG. 7(b)).
When the valve body 221 is removed from the hole 212 and the surface of the valve body 221 is spaced from the valve seat face 215, the one space is connected to the other space across the partition wall 211, thereby attaining an opened state (FIG. 7(a)).
The switch valves 200 are widely used for switching between the feeding start and the feeding stop of fluids (such as gases, liquids or the like).
In general, the partition wall 211 and the valve body 221 of the switch valve 200 are constructed of a metal, ceramic or the like. When such a switch valve 200 is repeatedly opened and closed, an engaging portion between the valve body 221 and the partition wall 211 is abraded, sealing performance of the switch valve 200 is not only deteriorated, but also dust is generated to cause contamination of the fluid.
In addition, when the on-off operation is repeated at a high temperature (240° C. to 400° C.), sealing faces are damaged, so that the sealing performance of the valve may be lost.
See, Japanese Patent Documents JP-A 2001-523768, JP-A 2003-525349, JP-A 2004-204289, JP-A 2005-29885, and JP-A 2006-111920.